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            <h2 class="title" style="clear: both"><a id="build_unix_macosx"></a>Mac OS X</h2>
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          <li>
            <span class="bold">
              <strong>When trying to link multiple
                Berkeley DB language interfaces (for example, Tcl,
                C++, Java, Python) into a single process, I get
                "multiple definitions" errors from dyld.</strong>
            </span>
            <p> 
                To fix this problem, set the environment variable
                MACOSX_DEPLOYMENT_TARGET to 10.3 (or your current
                version of OS X), and reconfigure and rebuild Berkeley
                DB from scratch. See the OS X ld(1) and dyld(1) man
                pages for information about how OS X handles symbol
                namespaces, as well as undefined and multiply-defined
                symbols.
            </p>
          </li>
          <li>
            <span class="bold">
              <strong>When trying to use system-backed
                shared memory on OS X I see failures about "too many
                open files".</strong>
            </span>
            <p>
	            The default number of shared memory segments on OS
                X is too low. To fix this problem, create a file named
                <code class="literal">/etc/sysctl.conf</code>, containing the
                variable assignments: 
            </p>
            <pre class="programlisting">kern.sysv.shmmax=134217728
kern.sysv.shmmin=1
kern.sysv.shmmni=32
kern.sysv.shmseg=32
kern.sysv.shmall=1024</pre>
            <p>
	            and then reboot the system.
            </p>
            <p>
	            Check the version of OS X carefully because some
	            versions require all five parameters to be set. 
            </p>
            <p>
                The <code class="literal">SHMMAX</code> variable should be set to a value
                that is an exact multiple of 4096. Some versions of
                OS X ignore the value if it is not an exact multiple. 
            </p>
            <p>
	            Please check and verify with the OS X documentation
	            on the proper setting of these parameters. In some
	            cases a reboot is necessary and in others it is possible
	            to change them dynamically using <code class="literal">sysctl</code>.
            </p>
            <p>
                The <code class="literal">/etc/sysctl.conf</code> file exists in OS X
                10.3.9 and later. If you are running a version of OS X
                previous to 10.3.x, edit the <code class="literal">/etc/rc</code>
                file and change the values in the following commands:
            </p>
            <pre class="programlisting">sysctl -w kern.sysv.shmmax=134217728
sysctl -w kern.sysv.shmseg=32</pre>
            <p>
	            and then reboot the system.
            </p>
            <p>
	            OS X system updates will overwrite <code class="literal">/etc/rc</code>
	            so any changes to the file must be redone after sytem updates. 
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